Sounds like a case of Hemorrhagic Septicemia. This is a bacterial infection in the blood stream and is caused by poor water and living conditions.
I strongly suggest you purchase the proper home for your Goldfish seeing as a bowl is comparable to actually putting dish soap in the water. It gives a fish no surface area for go bacterial growth, it can't hold a filter, they are far too small for Goldfish and in my opinion, they look outdated and ugly.
If you don't get a proper sized tank of 20 gallons with double filtration and your water cleaned up right (which would mean 50% water changes every day until the fish dies of stunting), your fish will die very soon. Also, you may need to use medicinal intervention like a fungus or bacterial med. You have to realize that you have 2 fish in a little bowl and most likely the illness will spread as a lot of bacterial ones do.
PLEASE, before ever purchasing any type of pet, research before you buy it or if you didn't get that change, research and change things for the better health of them. Check out the links.